JP7157760B2 - Resin composition, laminate and package - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition, a dispersion medium, a method for producing a resin composition, a laminate and a package.

Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") is excellent in oxygen barrier properties, transparency, oil resistance, antistatic properties, mechanical strength, etc., and is used in films, sheets, containers, etc. It is widely used as various packaging materials such as In recent years, EVOH has also been adopted as a material for containers for retorting food.

In order to improve the various properties required for EVOH, EVOH is made to contain an acid such as carboxylic acid or phosphoric acid, or a metal salt such as alkali metal salt or alkaline earth metal salt at an appropriate content. Various methods have been proposed (see JP-A-64-66262 and JP-A-2001-146539).

On the other hand, in retort containers using EVOH, the presence of moisture is known to reduce the oxygen shielding properties during and after retort treatment. Therefore, in order to prevent this deterioration of oxygen shielding properties, a resin composition has been proposed in which a desiccant or the like is added to EVOH (see Japanese Patent Application Laid-Open No. 2007-314788).

JP-A-64-66262 JP-A-2001-146539 Japanese Patent Application Laid-Open No. 2007-314788

However, conventional EVOH compositions containing metal salts and the like do not have sufficient formability (thermoformability) in thermoforming such as vacuum forming and pressure forming. On the other hand, it is conceivable to add a plasticizer or the like to improve the thermoformability of EVOH, but in this case, the plasticizer may bleed out from the obtained molded article. Further, when an EVOH composition is pelletized by melt extrusion molding or the like, EVOH and its degraded products may adhere to the screw, resulting in variation in the size and shape of the resulting pellets. Furthermore, in a retort container obtained using an EVOH composition containing a desiccant, if the desiccant is not sufficiently dispersed, the oxygen shielding property after retort treatment becomes insufficient.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a resin composition capable of obtaining a molded article having excellent thermoformability and suppressed bleed out, and a resin composition having such a resin. An object of the present invention is to provide a dispersion medium from which a composition can be obtained, a laminate using the resin composition, and a package containing the laminate.

The invention made to solve the above problems is an ethylene-vinyl alcohol copolymer (A), a number average molecular weight (Mn) of 1,000 or more and 100,000 or less, and a melting point of 40 ° C. or more and 120 ° C. or less. , containing an aliphatic polyester (B) having a structural unit represented by the following formula (I), the ethylene-vinyl alcohol copolymer (A) and the aliphatic polyester (B) for a total of 100 parts by mass A resin composition (α) in which the content of the aliphatic polyester (B) is 0.01 parts by mass or more and less than 30 parts by mass.
—(CH ₂ ) _n —OCO— (I)
(In formula (I), n represents an integer of 2 to 6.)

Since the resin composition (α) contains a predetermined amount of the aliphatic polyester (B), it is possible to obtain a molded article having excellent thermoformability and suppressed bleeding out. Although the reason for this is not clear, it is presumed that the above-mentioned aliphatic polyester (B), which has specific structures and physical properties, acts like a plasticizer and enhances thermoformability. Further, according to the resin composition (α), the content of the aliphatic polyester (B) is in the above range, and the melting point of the aliphatic polyester (B) is in the above range. bleed-out of the aliphatic polyester (B) from the resulting molded article is suppressed. Therefore, a good molded article can be molded from the resin composition (α).

The resin composition (α) further contains a metal compound (C), and the metal compound (C) with respect to a total of 100 parts by mass of the ethylene-vinyl alcohol copolymer (A) and the aliphatic polyester (B). It is preferable that the content of the metal element (C′) in the metal compound is 0.05 parts by mass or more and 20 parts by mass or less, and the metal compound (C) contains metal compound particles (C2).

When the resin composition (α) contains the metal compound (C) containing the metal compound particles (C2) in this way, the variation in the size of the pellets obtained when pelletizing by melt extrusion molding is reduced. , the melt moldability is enhanced. Although the reason for this is not clear, it is presumed that the metal compound particles (C2) readily interact with EVOH (A). It is also presumed that the aliphatic polyester (B) functions as a good dispersant for the metal compound particles (C2). As a result, the dispersibility of the metal compound particles (C2) is enhanced, etc., which suppresses the adhesion of EVOH and its degraded products to the screw during pelletizing, and stabilizes the strands, resulting in small variations in pellet size. It is assumed that In addition, the "melt moldability" refers not only to moldability when the resin composition is melt-molded into a shape such as a film, sheet, container, pipe, fiber, etc., but also to melt-kneading for preparing the resin composition. It also means that moldability when obtaining pellets etc. is also included. Moreover, the package formed from the resin composition (α) containing such a metal compound (C) has good oxygen shielding properties even after retort treatment.

The molar ratio (Ma/Mc) between the vinyl alcohol unit (Ma) in the ethylene-vinyl alcohol copolymer (A) and the metal element (Mc) in the metal compound (C) is 0.01 or more and 500 or less. is preferably By setting the molar ratio (Ma/Mc) within the above range, adhesion to the screw during pelletizing is further suppressed, and variation in pellet size is further reduced. In addition, the oxygen shielding property of the resulting package after retort treatment can be enhanced. The reason for this is presumed to be that by setting the molar ratio (Ma/Mc) within the above range, the interaction between the EVOH (A) and the metal compound particles (C2) is more favorable.

The mass ratio (B/C') between the aliphatic polyester (B) and the metal element (C') in the metal compound (C) is preferably 0.0005 or more and 5 or less. By setting the mass ratio (B/C') in the above range, the dispersibility of the metal compound particles (C2) is further enhanced, and thus adhesion to the screw during pelletizing is further suppressed, and variations in pellet size are suppressed. becomes smaller. In addition, the oxygen shielding property of the resulting package after retort treatment can be enhanced.

It is preferred that the metal component of the metal compound (C) contains sodium, magnesium, aluminum, potassium, calcium or a combination thereof. By using such a metal compound (C), the effects of the present invention such as thermoformability can be further enhanced.

The metal compound particles (C2) are sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium sulfate, sodium pyrophosphate, disodium succinate, sodium tartrate, trisodium citrate, magnesium sulfate, trimagnesium dicitrate, silicon Magnesium phosphate, trimagnesium phosphate, magnesium succinate, calcium lactate, nanoclays or combinations thereof are preferred. These ingredients act as desiccants. Therefore, when the metal compound particles (C2) contain such a component, it is possible to improve the oxygen shielding property of the resulting container or the like after retort treatment. In particular, since the resin composition (α) contains the aliphatic polyester (B), the dispersibility of the metal compound particles (C2) is good, and the thermoformability is also excellent, so that the resulting container or the like can be subjected to retort treatment. Oxygen shielding properties after drying are also fully exhibited.

Another invention made to solve the above problems is a dispersion medium for metal compound particles, comprising an ethylene-vinyl alcohol copolymer (A) and a number average molecular weight (Mn) of 1,000 or more and 100,000 Hereinafter, an aliphatic polyester (B) having a melting point of 40 ° C. or higher and 120 ° C. or lower and having a structural unit represented by the following formula (I) is included, and the above ethylene-vinyl alcohol copolymer (A) and the above The content of the aliphatic polyester (B) is 0.01 parts by mass or more and less than 30 parts by mass with respect to a total of 100 parts by mass of the aliphatic polyester (B).
—(CH ₂ ) _n —OCO— (I)
(In formula (I), n represents an integer of 2 to 6.)

The resin composition obtained by dispersing the metal compound particles in the dispersion medium has excellent thermoformability and melt moldability, and can give a molded article with suppressed bleeding out. Moreover, since the dispersion medium contains the aliphatic polyester (B), the metal compound particles can be well dispersed.

The dispersion medium preferably further contains a metal salt (C1). By further containing the metal salt (C1) in the dispersion medium, it is possible to further improve the thermoformability of the resulting resin composition.

The content of the metal element in the metal salt (C1) with respect to 100 parts by mass of the dispersion medium is preferably 0.0007 parts by mass or more and 0.05 parts by mass or less. By setting the content of the metal salt (C1) within the above range, it is possible to further improve the thermoformability, melt moldability, etc. of the resulting resin composition.

Another invention made to solve the above problems is a resin composition (β) containing the dispersion medium and metal compound particles (C2) dispersed in the dispersion medium. The resin composition (β) has good dispersibility of the metal compound particles (C2), and is excellent in thermoformability and melt moldability, and can give a molded article with suppressed bleed out. In addition, the package formed from the resin composition (β) has good oxygen shielding properties even after retort treatment.

Another invention made to solve the above problems is to obtain a dispersion medium by mixing a mixture of an ethylene-vinyl alcohol copolymer (A) and a metal salt (C1) with an aliphatic polyester (B). and a step of mixing the dispersion medium and the metal compound particles (C2), wherein the aliphatic polyester (B) has a number average molecular weight (Mn) of 1,000 or more and 100,000 or less and a melting point of 40 ° C. or more. 120 ° C. or less, and the aliphatic polyester (B) has a structural unit represented by the following formula (I), the ethylene-vinyl alcohol copolymer (A) and the aliphatic polyester (B) and a mass ratio (A/B) of 70/30 or more and 99.99/0.01 or less.
—(CH ₂ ) _n —OCO— (I)
(In formula (I), n represents an integer of 2 to 6.)

According to the production method, it is possible to produce a resin composition which is excellent in thermoformability and melt moldability and which can give a molded article with suppressed bleeding out. In addition, the resin composition obtained by the production method has good dispersibility of the metal compound particles (C2), and can form a package having good oxygen shielding properties after retort treatment.

Another invention made to solve the above problems is a barrier layer made of the resin composition (α) or the resin composition (β), and a thermoplastic resin disposed on at least one side of the barrier layer A laminate comprising a layer containing Since the laminate has a barrier layer composed of the resin composition (α) or the resin composition (β), it is excellent in thermoforming and has good oxygen shielding properties.

Another invention made to solve the above problem is a package including the laminate. Since the package has good oxygen shielding properties, it can be suitably used as a package for foods and the like.

The packaging is preferably for retort pouches. The package has good oxygen shielding properties after retort treatment, especially when the metal compound particles (C2) are a desiccant. Therefore, the package can be suitably used as a package for retort pouches.

According to the present invention, a resin composition capable of obtaining a molded article having excellent thermoformability and suppressed bleeding out, a dispersion medium capable of obtaining such a resin composition, and the above resin composition are used. A laminated body and a package including the laminated body can be provided.

<Resin composition (α)>
A resin composition (α) according to one embodiment of the present invention contains EVOH (A) and an aliphatic polyester (B). The resin composition (α) preferably further contains a metal compound (C). The resin composition has excellent thermoformability and can give a molded article with suppressed bleeding out. In addition, when the resin composition is pelletized by melt extrusion molding, adhesion to the screw is suppressed, and variation in the size of the obtained pellets is reduced, resulting in high melt moldability. The resin composition can be suitably used as a molding material such as a package.

(EVOH (A))
EVOH (A) is a polymer having ethylene units (--CH ₂ --CH ₂ --) and vinyl alcohol units (--CH ₂ --CHOH--) as main structural units. EVOH (A) may have other structural units as long as the effects of the present invention are not impaired.

The lower limit of the content of ethylene units in EVOH (A) (that is, the ratio of the number of ethylene units to the total number of monomer units in EVOH (A)) is preferably 20 mol%, more preferably 25 mol%. On the other hand, the upper limit of the content of ethylene units in EVOH (A) is preferably 65 mol%, more preferably 55 mol%. By setting the content of ethylene units in EVOH (A) to the above lower limit or more, the gas barrier properties, melt moldability, and suppression of occurrence of yellowing, etc., of the resulting molded article under high humidity can be enhanced. . Conversely, by making the content of ethylene units in EVOH (A) equal to or less than the above upper limit, the gas barrier properties of the resulting molded article can be further enhanced.

The lower limit of the vinyl alcohol unit content of EVOH (A) is preferably 35 mol %, more preferably 45 mol %. On the other hand, the upper limit of the vinyl alcohol unit content of EVOH (A) is preferably 80 mol %, more preferably 75 mol %. By setting the content of the vinyl alcohol unit of EVOH (A) to the above lower limit or more, the gas barrier properties of the resulting molded article can be further enhanced. By setting the content of the vinyl alcohol unit of EVOH (A) to the above upper limit or less, it is possible to improve the gas barrier properties, melt moldability, and suppression of occurrence of yellowing, etc., of the obtained molded article under high humidity conditions. can.

The lower limit of the degree of saponification of EVOH (A) (that is, the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH (A)) is preferably 90 mol%, and 99 mol%. more preferred. On the other hand, the upper limit of the degree of saponification of EVOH (A) may be 100 mol %. By setting the degree of saponification of EVOH (A) to the above lower limit or more, thermoformability and appearance characteristics can be enhanced.

The lower limit of the melt flow rate of EVOH (A) (210° C., under 2160 g load) is preferably 0.1 g/10 minutes, more preferably 0.5 g/10 minutes, and even more preferably 1 g/10 minutes. On the other hand, the upper limit of this melt flow rate is preferably 50 g/10 minutes, more preferably 20 g/10 minutes, and even more preferably 10 g/10 minutes. By setting the melt flow rate within the above range, the thermoformability can be further improved, and sufficient strength and the like can be imparted to the obtained molded article.

In addition, EVOH (A) may have units derived from monomers other than ethylene, vinyl esters and saponified products thereof as long as the object of the present invention is not hindered. When EVOH has the other monomer unit, the content of the other monomer unit with respect to all structural units of EVOH is preferably 30 mol% or less, more preferably 20 mol% or less. It is preferably 10 mol % or less, more preferably 5 mol % or less. Further, when EVOH has units derived from the other monomers, the lower limit may be 0.05 mol % or 0.1 mol %. Examples of the other monomers include alkenes such as propylene, butylene, pentene and hexene; 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, diacyloxy-1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy-2- methyl-1-butene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6- Alkenes having an ester group such as acyloxy-1-hexene, 5,6-diacyloxy-1-hexene, 1,3-diacetoxy-2-methylenepropane, or saponified products thereof; acrylic acid, methacrylic acid, crotonic acid, itaconic acid, etc. unsaturated acids or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefins such as vinylsulfonic acid, allylsulfonic acid, and methallylsulfonic acid Sulfonic acid or its salt; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, γ-methacryloxypropylmethoxysilane, etc. Vinylsilane compounds; alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride , vinylidene chloride and the like.

EVOH (A) may be a post-modified EVOH such as urethanized, acetalized, cyanoethylated, oxyalkylenated, and the like. Post-modified EVOH tends to have good melt moldability.

As EVOH (A), two or more types of EVOH having different ethylene unit content, degree of saponification, copolymer component, presence or absence of modification, type of modification, etc. may be mixed and used.

The lower limit of the content of EVOH (A) in the resin composition (α) is, for example, 50% by mass, preferably 70% by mass. By setting the content of EVOH (A) to the above lower limit or more, it is possible to impart sufficient oxygen shielding properties and the like to the resulting molded article. On the other hand, the upper limit of the content of EVOH (A) is preferably 99.9% by mass, for example. By setting the content of EVOH (A) to the upper limit or less, the thermoformability can be further improved.

(Aliphatic polyester (B))
Aliphatic polyester (B) is a polyester having no aromatic ring in the main chain of repeating units. Aliphatic polyester (B) is preferably polyester having no aromatic ring.

The lower limit of the number average molecular weight (Mn) of the aliphatic polyester (B) is 1,000, preferably 2,000, more preferably 3,000, even more preferably 4,000. When the number average molecular weight (Mn) of the aliphatic polyester (B) is at least the above lower limit, it is possible to sufficiently suppress bleeding out from the resulting molded article. On the other hand, the upper limit of this number average molecular weight (Mn) is 100,000, preferably 90,000, more preferably 80,000. When the number average molecular weight (Mn) of the aliphatic polyester (B) is equal to or less than the above upper limit, thermoformability, melt moldability, dispersibility of metal compound particles, etc. can be sufficiently improved.

The lower limit of the melting point of the aliphatic polyester (B) is 40°C, preferably 50°C, more preferably 60°C, and even more preferably 80°C in some cases. When the melting point of the aliphatic polyester (B) is at least the above lower limit, it is possible to sufficiently suppress bleeding out from the resulting molded article. On the other hand, the upper limit of this melting point is 120°C, preferably 110°C. When the melting point of the aliphatic polyester (B) is equal to or lower than the above upper limit, good plasticity can be exhibited during thermoforming, and thermoformability can be sufficiently improved.

Aliphatic polyester (B) has a structural unit (I) represented by the following formula (I). This structure can be identified by a nuclear magnetic resonance (NMR) method, pyrolysis gas chromatography, or the like.
—(CH ₂ ) _n —OCO— (I)
(In formula (I), n represents an integer of 2 to 6.)

Having the above structural unit in the aliphatic polyester (B) can sufficiently improve the thermoformability. The above n is preferably 3 to 6, more preferably 4 and 5, and even more preferably 4.

The aliphatic polyester (B) may be composed of repeating structural units (I), or may be composed of alternating repeating structural units (I) and other structural units (II). Structural units (II) include structural units represented by the following formula (II).
-R-CO- (II)
(In formula (II), R is a divalent aliphatic hydrocarbon group.)

Examples of the divalent aliphatic hydrocarbon group include ethanediyl groups, propanediyl groups, butanediyl groups, pentanediyl groups and other alkanediyl groups; ethenediyl groups and other alkenediyl groups; An alkanediyl group and the like can be mentioned.

Examples of the aliphatic polyester (B) composed of repeating structural units (I) include homopolymers of lactones, which are cyclic esters. Specific examples include polycaprolactone and polyvalerolactone. can be done.

As the aliphatic polyester (B) composed of alternating structural units (I) and structural units (II), a copolymer of an aliphatic diol and an aliphatic dicarboxylic acid can be mentioned. Examples of aliphatic diols include 1,2-ethanediol (ethylene glycol), 1,4-butanediol, and 1,6-hexanediol. Examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid and adipic acid. Specific examples of the aliphatic polyester (B) composed of alternating structural units (I) and structural units (II) include polyethylene succinate and polybutylene succinate.

The aliphatic polyester (B) may have modified ends and side chains. In addition, the aliphatic polyester (B) may have a functional group containing an aromatic ring at the end or side chain. Examples of the terminal functional group that the aliphatic polyester (B) may have include an organic group having one or more hydroxy groups, a polysiloxanyl group having one or more hydroxy groups, and the like. Organic groups having a hydroxy group include one or more hydroxyalkyl groups. When the aliphatic polyester (B) has such terminal functional groups, the dispersibility of the metal compound particles can be enhanced.

The lower limit of the content of the aliphatic polyester (B) with respect to a total of 100 parts by mass of the EVOH (A) and the aliphatic polyester (B) is 0.01 parts by mass, preferably 0.02 parts by mass, and 0.03 parts by mass. is more preferred. When the content of the aliphatic polyester (B) is at least the above lower limit, the aliphatic polyester (B) exhibits good plasticity during thermoforming and can sufficiently improve thermoformability. On the other hand, this content is less than 30 parts by mass, preferably less than 20 parts by mass. The upper limit of this content is also preferably 20 parts by mass, more preferably 15 parts by mass, still more preferably 10 parts by mass, and even more preferably 5 parts by mass. When the upper limit of the content of the aliphatic polyester (B) is within the above range, it is possible to sufficiently suppress bleed out from the resulting molded article and improve thermoformability.

(Metal compound (C))
The metal compound (C) preferably contains a metal salt (C1) and metal compound particles (C2). The metal component of the metal compound (C) preferably contains sodium, magnesium, aluminum, potassium, calcium or a combination thereof, more preferably sodium, magnesium, calcium or a combination thereof. These metal components may be contained in one or both of the metal salt (C1) and the metal compound particles (C2).

(Metal salt (C1))
The metal salt (C1) can improve moldability, interlayer adhesion, appearance and the like of the resin composition (α). The metal salt (C1) exists in the form of dissociated anions and cations or in the form of fine particles. When the metal salt (C1) exists in the form of fine particles, the average particle size is usually 0.5 μm or less, and may be 0.1 μm or less.

Examples of the metal salt (C1) include alkali metal salts, alkaline earth metal salts, d-block metal salts listed in the fourth period of the periodic table, and the like. Among these, alkali metal salts and alkaline earth metal salts are preferred, and alkali metal salts are more preferred. When these metal salts are contained, the interlaminar adhesion and the like of the resin composition (α) can be enhanced.

Alkali metal salts include, for example, aliphatic carboxylates, aromatic carboxylates, phosphates, metal complexes of lithium, sodium, potassium and the like. Specific examples of the alkali metal salt include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like.

Examples of alkaline earth metal salts include carboxylates and phosphates of magnesium, calcium, barium, beryllium, and the like.

Metal salts of d-block metals listed in the fourth period of the periodic table include, for example, carboxylates, phosphates, acetylacetonates of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, etc. nath salt and the like.

When the resin composition (α) contains the metal salt (C1), the lower limit of the content of the metal element in the metal salt (C1) is preferably 1 ppm, more preferably 5 ppm, relative to the EVOH (A). 10 ppm is more preferred, and 20 ppm is particularly preferred. The upper limit of the content of the metal element in the metal salt (C1) is preferably 10,000 ppm, more preferably 5,000 ppm, even more preferably 1,000 ppm, and particularly preferably 500 ppm, relative to EVOH (A). When the content of the metal salt (C1) is within the above range, the thermal stability during recycling tends to be better while maintaining better interlayer adhesion.

(Metal compound particles (C2))
The metal compound particles (C2) usually exist in the form of particles dispersed in the resin composition (α). The lower limit of the average particle size of the metal compound particles (C2) is preferably 1 µm, more preferably 1.1 µm, and even more preferably 1.2 µm. On the other hand, the upper limit of this average particle size is preferably 15 μm, more preferably 12 μm, and even more preferably 8 μm. When the average particle size of the metal compound particles (C2) is in the above range, it has good dispersibility, the thermoformability and melt moldability of the resin composition (α), and the oxygen content after retort treatment of the resulting package. Shielding properties are further enhanced.

The metal compound that constitutes the metal compound particles (C2) is not particularly limited, and includes metal oxides, metal nitrides, metal carbides, alloys, metal salts, etc. Metal salts are preferred.

Specifically, the metal compound particles (C2) include sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium sulfate, sodium pyrophosphate, disodium succinate, sodium tartrate, trisodium citrate, magnesium sulfate, and dicitric acid. Trimagnesium, magnesium silicate, trimagnesium phosphate, magnesium succinate, calcium lactate, nanoclay, sodium phosphate, sodium polyphosphate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, lithium polyphosphate, phosphorus potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium polyphosphate, calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium polyphosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate , ammonium polyphosphate, and the like. Here, polyphosphates include diphosphates (pyrophosphates), triphosphates (tripolyphosphates), and the like. Among these, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium sulfate, sodium pyrophosphate, disodium succinate, sodium tartrate, trisodium citrate, magnesium sulfate, trimagnesium dicitrate, magnesium silicate, trimagnesium phosphate , magnesium succinate, calcium lactate, nanoclay or a combination thereof, more preferably particles of disodium hydrogen phosphate, disodium succinate, trimagnesium dicitrate, calcium lactate or a combination thereof, More preferred are particles of disodium hydrogen phosphate. These components suitably function as desiccants and capture water that has entered during retort treatment, thereby suppressing increases in the water content of EVOH (A) in the resin composition (α). Therefore, by using the metal compound particles (C2) having such components, it is possible to improve the oxygen shielding property of the resulting container after retort treatment.

The lower limit of the content ratio of the metal compound particles (C2) in the metal compound (C) is preferably 50% by mass, more preferably 90% by mass, and even more preferably 95% by mass. By making the content ratio of the metal compound particles (C2) in the metal compound (C) equal to or higher than the above lower limit, the effect of containing the metal compound particles (C2) can be enhanced. On the other hand, the upper limit of the content ratio of the metal compound particles (C2) in the metal compound (C) may be, for example, 99.999% by mass.

The lower limit of the content of the metal element (C') in the metal compound (C) with respect to a total of 100 parts by mass of the EVOH (A) and the aliphatic polyester (B) is preferably 0.05 parts by mass, and 0.1 parts by mass. parts is more preferred, 0.3 parts by mass is even more preferred, and 0.5 parts by mass is even more preferred. When the content of the metal element (C') in the metal compound (C) is at least the above lower limit, the adhesion to the screw during melt-kneading is suppressed, and the resulting pellets have less variation. Moldability is improved. In addition, it is possible to improve the oxygen shielding property of the resulting molded article. On the other hand, the upper limit of this content is preferably 20 parts by mass, more preferably 12 parts by mass, still more preferably 10 parts by mass, even more preferably 8 parts by mass, and even more preferably 3 parts by mass. When the content of the metal element (C') in the metal compound (C) is equal to or less than the above upper limit, the dispersibility of the metal compound (C) is enhanced, thereby further enhancing the melt moldability and reducing the size of the pellet. Variation is reduced, and the oxygen shielding property of the resulting package after retort treatment is enhanced.

The lower limit of the molar ratio (Ma/Mc) between the vinyl alcohol unit (Ma) in the EVOH (A) and the metal element (Mc) in the metal compound (C) is preferably 0.01, more preferably 0.1. Preferably, 1 is more preferable, 3 is even more preferable, and 5 is particularly preferable. On the other hand, the upper limit of this molar ratio (Ma/Mc) is preferably 500, more preferably 200, even more preferably 130, and even more preferably 30. By setting the molar ratio (Ma/Mc) within the above range, the dispersibility of the metal compound particles (C2) is improved and the melt moldability is enhanced. Therefore, adhesion to the screw during pelletizing is further suppressed, and variation in pellet size is further reduced. In addition, the oxygen shielding property of the resulting package after retort treatment is also improved due to the enhanced melt moldability.

The lower limit of the mass ratio (B/C') between the aliphatic polyester (B) and the metal element (C') in the metal compound (C) is preferably 0.0005, more preferably 0.001, and 0.001. 01 is more preferred, 0.05 is even more preferred, and 0.1 is even more preferred. On the other hand, the upper limit of this mass ratio (B/C') is preferably 5, more preferably 3, even more preferably 1, and even more preferably 0.5. By setting the mass ratio (B/C') within the above range, the dispersibility of the metal compound particles (C2) is improved and the melt moldability is enhanced. In addition, the oxygen shielding property of the resulting package after retort treatment is also improved due to the enhanced melt moldability.

(other ingredients)
The resin composition may further contain components other than EVOH (A), aliphatic polyester (B) and metal compound (C). Other ingredients include acids, boron compounds, plasticizers, fillers, antiblocking agents, lubricants, stabilizers, antioxidants, surfactants, colorants, fluorescent brighteners, UV absorbers, antistatic agents, fillers. agents, desiccants, cross-linking agents, various fibers, and resins other than EVOH (A) and aliphatic polyester (B). In the resin composition (α), the upper limit of the content of components other than EVOH (A), aliphatic polyester (B) and metal compound (C) is preferably 10,000 ppm. 1,000 ppm may be more preferred, and 100 ppm may be even more preferred. In some cases, the other components mentioned above may not be contained. By setting the content of the other component to the above upper limit or less, the effect of the present invention can be exhibited more sufficiently.

As the acid, a carboxylic acid compound and a phosphoric acid compound are preferable from the viewpoint of enhancing the thermal stability during melt molding of the resin composition (α). When the resin composition (α) contains a carboxylic acid compound, the lower limit of the carboxylic acid content is preferably 1 ppm, more preferably 10 ppm, and even more preferably 50 ppm. Moreover, the upper limit of the carboxylic acid content is preferably 10,000 ppm, more preferably 1,000 ppm, and even more preferably 500 ppm. When the resin composition (α) contains a phosphoric acid compound, the lower limit of the content of the phosphoric acid compound (content in terms of phosphate root) is preferably 1 ppm, more preferably 10 ppm, and even more preferably 30 ppm. On the other hand, the upper limit of the content of the phosphoric acid compound is preferably 10,000 ppm, more preferably 1,000 ppm, and even more preferably 300 ppm. When the resin composition (α) contains the carboxylic acid compound or the phosphoric acid compound within the above range, the thermal stability during melt molding tends to be better.

When the resin composition (α) contains the boron compound, the content (content in terms of boron) is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 50 ppm or more. Moreover, the content of the boron compound is preferably 2,000 ppm or more, more preferably 1,000 ppm or more, and even more preferably 500 ppm or more. When the content of the boron compound is within the above range, the thermal stability during melt molding tends to be improved.

Specific examples of the other resins include thermoplastic resins such as polyolefins, polyamides, polyesters, polystyrenes, polyvinyl chlorides, acrylic resins, polyurethanes, polycarbonates, and polyvinyl acetates. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and 2 parts by mass or less with respect to the resin composition (α). Most preferred.

The shape of the resin composition (α) is not particularly limited, and may be in the form of solution, paste, powder, pellet, or the like. is preferably

<Method for producing resin composition (α)>
The method for producing the resin composition (α) is not particularly limited, and it can be obtained by mixing each component, but it is preferably produced by the following method.

That is, the method for producing a resin composition according to one embodiment of the present invention includes:
a step of synthesizing EVOH (A) (step 1);
Step of mixing EVOH (A) and metal salt (C1) (Step 2)
A step of obtaining a dispersion medium (step 3) by mixing a mixture of EVOH (A) and a metal salt (C1) with an aliphatic polyester (B), and mixing the dispersion medium and the metal compound particles (C2) Step (Step 4)
Prepare.

(Step 1)
Step 1 is a step of synthesizing EVOH (A). EVOH (A) can be synthesized by a conventionally known method. Usually, EVOH (A) can be obtained by copolymerizing ethylene and vinyl ester and saponifying the obtained ethylene-vinyl ester copolymer.

As the method for copolymerizing ethylene and vinyl ester, known methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be employed. A bulk polymerization method or a solution polymerization method, in which polymerization is carried out in a solvent-free solution or in a solution such as alcohol, is usually employed. When obtaining a modified ethylene-vinyl ester copolymer with a high degree of polymerization, one option is to adopt an emulsion polymerization method.

Solvents used in the solution polymerization method are not particularly limited, but alcohols are preferably used, and lower alcohols such as methanol, ethanol and propanol are more preferably used. The amount of the solvent used in the polymerization reaction solution may be selected in consideration of the desired viscosity average degree of polymerization of EVOH and the chain transfer of the solvent, and the weight ratio of the solvent to the total monomers contained in the reaction solution ( solvent/total monomer) is selected from the range 0.01-10, preferably from the range 0.05-3.

Examples of catalysts used for polymerization include 2,2-azobisisobutyronitrile, 2,2-azobis-(2,4-dimethylvaleronitrile), 2,2-azobis-(4-methoxy-2,4 -dimethylvaleronitrile), 2,2-azobis-(2-cyclopropylpropionitrile) and other azo initiators; isobutyryl peroxide, cumyl peroxyneodecanoate, diisopropyl peroxycarbonate, di-n- Organic peroxide initiators such as propyl peroxydicarbonate, t-butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide and t-butyl hydroperoxide can be used.

The polymerization temperature is 20 to 90°C, preferably 40 to 70°C. The polymerization time is 2 to 15 hours, preferably 3 to 11 hours. The polymerization rate is 10 to 90%, preferably 30 to 80%, based on the charged vinyl ester. The resin content in the solution after polymerization is 5-85%, preferably 20-70%.

After polymerization for a predetermined time or after reaching a predetermined polymerization rate, a polymerization inhibitor is added as necessary, unreacted ethylene gas is removed by evaporation, and unreacted vinyl ester is removed. As a method for removing unreacted vinyl ester, for example, the above copolymer solution is continuously supplied at a constant rate from the upper part of a tower packed with Raschig rings, and organic solvent vapor such as methanol is blown from the lower part of the tower. A method of distilling off a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester from the top and taking out a copolymer solution from which the unreacted vinyl ester has been removed from the bottom of the column is adopted.

Next, an alkali catalyst is added to the copolymer solution to saponify the copolymer. The saponification method can be either a continuous method or a batch method. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, alkali metal alcoholate, and the like.

The saponification conditions are, for example, in the case of a batch system, the concentration of the copolymer solution is 10 to 50%, the reaction temperature is 30 to 65° C., and the amount of catalyst used is 0.02 to 1.0 per mole of the vinyl ester structural unit. mol, saponification time is 1 to 6 hours.

Since EVOH after the saponification reaction contains an alkali catalyst, by-product salts such as sodium acetate and potassium acetate, and other impurities, these are preferably removed by neutralization and washing as necessary. Here, when the EVOH after the saponification reaction is washed with water such as ion-exchanged water containing almost no metal ions, chloride ions, etc., a part of sodium acetate, potassium acetate, etc. may remain.

(Step 2)
Step 2 is a step of mixing EVOH (A) and metal salt (C1). The method of mixing the EVOH (A) and the metal salt (C1) is not particularly limited, and examples thereof include a method of immersing pellets or strands of the EVOH (A) in a solution in which the metal salt (C1) is dissolved. . This method is preferable in that the metal salt (C1) can be homogeneously dispersed in the EVOH (A). Water is preferably used as the solvent for dissolving the metal salt (C1).

Another method of mixing the EVOH (A) and the metal salt (C1) includes a method of adding the metal salt (C1) and kneading when preparing pellets or the like containing the EVOH (A). Examples of the method of addition include a method of adding as a dry powder, a method of adding in the form of a paste impregnated with a solvent, a method of adding in a state of being suspended in a liquid, a method of dissolving in a solvent and adding as a solution, and the like. exemplified.

In addition, a mixture may be obtained by leaving metal salts generated in the saponification step or the like when synthesizing EVOH (A). Furthermore, a mixture may be obtained by combining each of the above methods. Alternatively, a commercially available EVOH composition containing metal salt (C1) may be prepared and used as a mixture.

(Step 3)
Step 3 is a step of mixing the mixture obtained in Step 2 and the aliphatic polyester (B). Thereby, a dispersion medium is obtained. The mixing method is not particularly limited, and can be carried out using a Henschel mixer or a tumbler. It can also be carried out by melt-kneading. For melt-kneading, a general apparatus used for melt-kneading resins can be employed. As a kneading device, a continuous kneading device such as a single-screw extruder or a twin-screw extruder may be used, or a batch-type kneading device such as a Banbury mixer may be used.

The temperature during melt-kneading is not particularly limited as long as it is a temperature at which EVOH (A) can be melted. By setting the melt-kneading temperature to 190° C. or higher, the EVOH (A) is sufficiently melted. The lower limit of the melt-kneading temperature is more preferably 210°C. On the other hand, by setting the melt-kneading temperature to 260° C. or lower, decomposition of EVOH (A) and the like can be suppressed. The upper limit of the melt-kneading temperature is more preferably 245°C.

The lower limit of the mass ratio (A/B) between EVOH (A) and aliphatic polyester (B) in step 3 is 70/30, preferably 80/20, more preferably 90/10. On the other hand, the upper limit of this mass ratio (A/B) is 99.99/0.01, preferably 99.98/0.02, more preferably 99.97/0.03.

(Step 4)
Step 4 is a step of mixing the dispersion medium obtained in Step 3 and the metal compound particles (C2). The method of mixing the dispersion medium and the metal compound particles (C2) is not particularly limited, but usually melt-kneading can be suitably carried out. An aqueous solution of the metal particle compound (C2) may be added to the dispersion medium. From the viewpoint of handleability, melt moldability of the resin composition obtained, oxygen shielding property after retort treatment, etc., it is preferable to add powdery metal compound particles (C2) to the dispersion medium. For melt-kneading, a general apparatus used for melt-kneading resins can be employed. As a kneading device, a continuous kneading device such as a single-screw extruder or a twin-screw extruder may be used, or a batch-type kneading device such as a Banbury mixer may be used.

The temperature during melt-kneading is not particularly limited as long as it is a temperature at which EVOH (A) can be melted. By setting the melt-kneading temperature to 190° C. or higher, the EVOH (A) is sufficiently melted. The lower limit of the melt-kneading temperature is more preferably 210°C. On the other hand, by setting the melt-kneading temperature to 260° C. or lower, decomposition of EVOH (A) and the like can be suppressed. The upper limit of the melt-kneading temperature is more preferably 245°C.

The steps 3 and 4 can be performed continuously. That is, steps 3 and 4 can be performed by adding the aliphatic polyester (B) to a mixture of EVOH (A) and the metal salt (C1), and then adding the metal compound particles (C2). .

The preferred form of each component is as described above as the embodiment of the "resin composition (α)".

The resin composition (α) can also be obtained by other production methods. For example, when the resin composition (α) does not contain the metal compound (C), the EVOH (A) and the aliphatic polyester (B) are mixed by a known method such as melt kneading or dry blending to obtain a resin. A composition (α) can be obtained. Further, the aliphatic polyester (B) and the metal compound (C2) may be added simultaneously to the mixture of EVOH (A) and the metal salt (C1), or the metal compound (C2) and the aliphatic polyester ( B) may be added in order. Mixing of each component may be performed by dry blending. Furthermore, when using commercially available EVOH (A), step 1 may not be performed, and when not containing metal salt (C1), step 2 may not be performed.

Further, in steps 2 to 4, etc., the other components described above can be mixed together. For example, a method of adding an acid or a boron compound to an EVOH-containing composition and kneading the composition when preparing pellets or the like of the composition is preferably employed. The method of adding to this composition is also not particularly limited, but a method of adding as a dry powder, a method of adding in the form of a paste impregnated with a solvent, a method of adding in a state of being suspended in a liquid, a method of adding in a state of being dissolved in a solvent A method of adding as a solution, a method of immersing in a solution, and the like are exemplified. From the viewpoint of uniform dispersion among these, the method of dissolving in a solvent and adding as a solution or the method of immersing in the solution are preferable. Although the solvent used in these methods is not particularly limited, water is preferably used from the viewpoints of solubility of additives, cost advantages, ease of handling, safety in the working environment, and the like.

<Dispersion medium>
A dispersion medium according to one embodiment of the present invention is a dispersion medium for metal compound particles and contains EVOH (A) and an aliphatic polyester (B). In the dispersion medium, the content of the aliphatic polyester (B) is 0.01 parts by mass or more and less than 30 parts by mass with respect to a total of 100 parts by mass of the EVOH (A) and the aliphatic polyester (B). The resin composition obtained by dispersing the metal compound particles in the dispersion medium has excellent thermoformability and can give a molded article with suppressed bleeding out. Moreover, since the dispersion medium contains the aliphatic polyester (B), the metal compound particles can be well dispersed, and the melt moldability is also excellent. From the resin composition obtained by dispersing the metal compound particles in the dispersion medium, it is possible to obtain a package having high oxygen shielding properties after retort treatment.

The dispersion medium preferably further contains a metal salt (C1). The lower limit of the content of the metal element in the metal salt (C1) with respect to 100 parts by mass of the dispersion medium is preferably 0.0007 parts by mass, more preferably 0.001 parts by mass. On the other hand, the upper limit of this content is preferably 0.05 parts by mass, more preferably 0.04 parts by mass. By including the metal salt (C1) in the dispersion medium preferably within the above range, it is possible to further improve the thermoformability of the resulting resin composition.

The dispersion medium can be regarded as the above-described "resin composition (α)" excluding the metal compound particles (C2). Therefore, the detailed or preferred form of EVOH (A), aliphatic polyester (B), metal salt (C1), etc. in the dispersion medium, the total content of EVOH (A) and aliphatic polyester (B) The content of the polyester (B), optional components, etc. can be the same as those of the resin composition (α).

The lower limit of the content of EVOH (A) in the dispersion medium is, for example, 50% by mass, preferably 70% by mass. By setting the content of EVOH (A) to the above lower limit or more, it is possible to impart sufficient oxygen shielding properties and the like to the molded article obtained from the resin composition containing this dispersion medium. On the other hand, the upper limit of the content of EVOH (A) is, for example, 99.9% by mass. and so on.

In the dispersion medium, the upper limit of the content of components other than EVOH (A), aliphatic polyester (B) and metal salt (C1) is preferably 10,000 ppm, more preferably 1,000 ppm. Sometimes 100 ppm is even more preferable. In some cases, the other components mentioned above may not be contained. By setting the content of the other component to the above upper limit or less, the effect of the present invention can be exhibited more sufficiently.

<Method for producing dispersion medium>
A method for producing the dispersion medium is not particularly limited, and the dispersion medium can be obtained by mixing each component. For example, the dispersion medium can be obtained by steps 1 to 3 in the method for producing the resin composition described above. Alternatively, it can be obtained by melt-kneading the EVOH (A) and the aliphatic polyester (B). For the melt-kneading method, the method described in the method for producing the resin composition (α) can be referred to.

<Resin composition (β)>
A resin composition (β) according to one embodiment of the present invention is a resin composition containing the dispersion medium and metal compound particles (C2) dispersed in the dispersion medium. The resin composition (β) has good dispersibility of the metal compound particles (C2), and can give a molded article having excellent thermoformability and suppressed bleeding out. In addition, the resin composition is excellent in melt moldability, and a package having high oxygen shielding properties after retort treatment can be obtained.

The resin composition (β) includes, as specific components, EVOH (A), aliphatic polyester (B), metal compound (C) (metal salt (C1) and metal compound particles (C2)), and other optional components. including. That is, the component composition of the resin composition (β) is substantially the same as that of the resin composition (α) described above. Detailed and suitable forms such as each component and content of the resin composition (β) are the same as those of the resin composition (α) described above.

<Method for producing resin composition (β)>
The method for producing the resin composition (β) is not particularly limited, and the resin composition (β) can be obtained, for example, by step 4 in the method for producing the resin composition described above. That is, it can be obtained by mixing the dispersion medium and the metal compound particles (C2) by melt-kneading or the like. Alternatively, the production of the dispersion medium and the production of the resin composition (β) may be carried out continuously. That is, for example, the aliphatic polyester (B) is added to the mixture (I) of the EVOH (A) and the metal salt (C1) and melt-kneaded to obtain a dispersion medium, followed by The resin composition (β) may be obtained by adding the metal compound particles (C2) to and melt-kneading. For the melt-kneading method, the method described in the method for producing the resin composition (α) can be referred to.

<How to use the resin composition>
The resin composition (α) and the resin composition (β) (hereinafter both resin compositions may be collectively referred to simply as “resin composition”) are melt-molded into films, sheets, containers, pipes, fibers, etc. Molded into various moldings. Extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding and the like can be used as the melt molding method. The melt-molding temperature varies depending on the melting point of EVOH (A) and the like, but is preferably about 150 to 270°C.

<Laminate>
Although the resin composition can be used as a molded body consisting of a single layer of the resin composition, it is preferable to use a laminate containing at least one layer of the resin composition. That is, the laminate according to one embodiment of the present invention comprises a barrier layer made of the resin composition, and a layer containing a thermoplastic resin (thermoplastic resin layer) disposed on at least one side of the barrier layer. It is a laminated body provided.

As the layer structure of the laminate, Barrier is the barrier layer, Tie is the adhesive resin layer, and P is the thermoplastic resin layer. /Barrier/Tie/P, etc., but not limited thereto. Each layer indicated herein may be a single layer, or in some cases may be multiple layers.

Examples of the thermoplastic resin include polyolefin, polystyrene, polyester, polyamide, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, and polyacrylonitrile, and polyolefin is preferred.

Polyolefins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, polybutene, polymethylpentene, ionomers, and the like. be able to.

The adhesive resin forming the adhesive resin layer is not particularly limited as long as it can adhere the barrier layer and the thermoplastic resin layer, but carboxylic acid-modified polyolefin is preferable. Carboxylic acid-modified polyolefin is a modified olefin polymer containing a carboxy group obtained by chemically bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer (for example, by addition reaction or graft reaction). Say things.

The laminate can be obtained by, for example, co-extrusion or co-injection of the resin composition forming each layer. Further, various molded products (films, sheets, tubes, bottles, etc.) can be obtained by secondary processing of the laminates such as sheets, films, pipes, and parisons. Molded articles obtained by secondary processing include, for example, the following. A molded article obtained by such secondary processing is also included in the laminate as an embodiment of the present invention.

(1) A co-stretched sheet or film obtained by stretching the laminate (film, sheet, etc.) uniaxially or biaxially and optionally heat-treating it (2) The laminate (film, sheet, etc.) Rolled sheet or film obtained by rolling (3) Tray cup-shaped container obtained by thermoforming the laminate (film, sheet, etc.) by vacuum forming, air pressure forming, vacuum pressure forming, etc. (4) Laminate Bottles and cup-shaped containers obtained by stretch blow molding a body (pipe, etc.) (5) Bottle-shaped container obtained by biaxially stretch blow molding the laminate (parison, etc.)

The use of the laminate is not particularly limited, and it is suitably used as a package such as a packaging film, a deep-drawn container, a cup-shaped container, and a bottle. Among others, it is suitable as a packaging body (container) for packaging contents, especially foods, which are susceptible to deterioration due to oxygen.

In particular, the package is particularly suitable as a package for retort pouches. As the retort treatment, steam retort treatment, water cascade retort treatment, microwave retort treatment, and the like are employed in addition to normal retort treatment in which the material is heated to 100° C. or higher and pressurized. In addition, the package is suitable not only for retort treatment, but also as a package for hot filling, sterilization, and boiling.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

The number average molecular weight and melting point (Tm) of the polyester and the average particle size of the metal compound particles were measured by the following methods.

(Number average molecular weight)
The number average molecular weight of each polyester was measured by gel permeation chromatography (GPC) and obtained as a molecular weight conversion value of polymethyl methacrylate. The measurement conditions are as follows.
Apparatus: Gel permeation chromatography "HLC-8320" manufactured by Tosoh Corporation
Column: Two "TSKgel GMH _HR -H (S)" manufactured by Tosoh Corporation Column temperature: 40 ° C.
Mobile phase: hexafluoroisopropanol, flow rate: 0.2 mL/min Detector: RI, sample concentration: 0.1 wt% (hexafluoroisopropanol solution containing 20 mM trifluoroacetate sodium salt)

(Melting point (Tm))
For each polyester, a differential scanning calorimeter “Q2000” manufactured by TA Instruments was used to raise the temperature from 20° C. to 250° C. at a rate of 10° C./min, and the melting point (Tm) was obtained from the measured peak temperature.

(Average particle size)
Using each resin composition as a material, the extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 3.5, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. was used under the following conditions. to obtain a single layer film.
Cylinder temperature: supply section 180°C, compression section 220°C, metering section 220°C
Die temperature: 220°C
Screw rotation speed: 40 rpm
Discharge rate: 1.2 kg/hour Take-up roll temperature: 80°C
Take-up roll speed: 3.0 m/min Film thickness: 20 μm
Using a shape measuring laser microscope "VK-X200" (non-contact type, manufactured by Keyence Corporation), the obtained single layer film was observed to measure the particle size of the metal compound particles (C2). The measurement was performed at n=10, and the average value was taken as the average particle size.

<Synthesis Example 1> Synthesis of EVOH (polymerization of ethylene-vinyl acetate copolymer)
83.0 kg of vinyl acetate and 26.6 kg of methanol were charged into a 250 L pressurized reactor equipped with a stirrer, nitrogen inlet, ethylene inlet, initiator addition port and delay (sequential addition) solution addition port, and the temperature was raised to 60°C. After that, the inside of the system was replaced with nitrogen by bubbling nitrogen for 30 minutes. Then, ethylene was charged so that the reactor pressure was 3.6 MPa. As an initiator, 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) (AMV) is dissolved in methanol to prepare an initiator solution with a concentration of 2.5 g/L, and bubbling with nitrogen gas. was performed to replace nitrogen. After adjusting the internal temperature of the polymerization vessel to 60° C., 362 mL of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 3.6 MPa and the polymerization temperature at 60° C., and the polymerization was carried out by continuously adding AMV at 1120 mL/hr using the above initiator solution. After 5.0 hours, when the polymerization rate reached 40%, the mixture was cooled to terminate the polymerization. After the reactor was opened to deethyleneize, nitrogen gas was bubbled through to completely deethylenize. Next, the obtained copolymer solution was continuously supplied from the upper part of the column packed with Raschig rings, methanol was blown in from the lower part of the column, and the mixed vapor of methanol and unreacted vinyl acetate monomer was discharged from the top of the column. A methanol solution of ethylene-vinyl acetate copolymer (EVAc) from which the reactive vinyl acetate monomer was removed was obtained.

(Saponification)
Methanol was added to the resulting EVAc solution to adjust the concentration to 15% by mass, and 253.4 kg of a methanol solution of EVAc (38 kg of EVAc in the solution) was added with 76.6 L (relative to the vinyl acetate unit in EVAc). EVAc was saponified by adding an alkaline solution (a 10% by mass methanol solution of NaOH) with a molar ratio of 0.4) and stirring at 60° C. for 4 hours. After 6 hours from the start of the reaction, 9.2 kg of acetic acid and 60 L of water were added to neutralize the above reaction solution and stop the reaction.

(Washing)
The neutralized reaction liquid was transferred from the reactor to a drum can and allowed to stand at room temperature for 16 hours to cool and solidify into a cake. Thereafter, the cake-like resin was deliquored using a centrifugal separator ("H-130" manufactured by Kokusan Centrifugal Co., Ltd., 1200 rpm). Next, a step of washing the resin while continuously supplying ion-exchanged water from above to the center of the centrifuge was performed for 10 hours. Ten hours after the start of washing, the conductivity of the washing liquid was 30 μS/cm (measured with "CM-30ET" manufactured by Toa Denpa Kogyo Co., Ltd.).

(granulation)
The powdery EVOH thus obtained was dried at 60° C. for 48 hours using a dryer. 20 kg of dry powdery EVOH was dissolved in 80 L of water/methanol mixed solution (mass ratio: water/methanol=4/6) with stirring at 80° C. for 12 hours. Next, the stirring was stopped and the temperature of the dissolving tank was lowered to 65° C. and allowed to stand for 5 hours to defoam the water/methanol solution of EVOH. Then, it is extruded into a water/methanol mixed solution (mass ratio: water/methanol = 9/1) at 5°C from a metal plate having a circular opening with a diameter of 3.5 mm to deposit it in a strand shape and cut it. to obtain hydrous EVOH pellets having a diameter of about 4 mm and a length of about 5 mm.

(purification)
40 kg of the hydrous EVOH pellets thus obtained and 150 L of ion-exchanged water are placed in a metal drum can having a height of 900 mm and an opening diameter of 600 mm. rice field. Next, 150 L of a 1 g/L acetic acid aqueous solution was added to 30 kg of the hydrous EVOH pellets, and an operation of washing and deliquoring while stirring at 25° C. for 2 hours was repeated twice. Furthermore, 150 L of ion-exchanged water was added to 30 kg of hydrous EVOH pellets, and the operation of washing and deliquoring while stirring at 25 ° C. for 2 hours was repeated six times to remove impurities such as by-products in the saponification process. A removed hydrous EVOH pellet (w-EVOH-1) was obtained. After the sixth washing, the conductivity of the washing liquid was measured with "CM-30ET" manufactured by Toa Denpa Kogyo Co., Ltd. As a result, the conductivity of the washing liquid was 3 μS/cm. The water content of the obtained hydrous EVOH pellets was 200% by mass.

<Preparation example>
10 hydrous EVOH pellets having a water content of 200% obtained in Synthesis Example 1 were added to 94.5 L of an aqueous solution in which the respective components were dissolved in water so that 0.364 g/L of acetic acid and 0.455 g/L of sodium acetate were dissolved. 0.5 kg was added and immersion was performed at 25° C. for 6 hours with occasional stirring. The water-containing EVOH pellets after immersion were dehydrated by centrifugal deliquoring, dried in a hot air dryer at 80°C for 3 hours, and then dried at 120°C for 24 hours. As a result, pellets (EVOH-1) of a dry EVOH resin composition, which is a mixture of EVOH and a metal salt, were obtained. The vinyl alcohol unit content and the degree of saponification of the EVOH used in this example were analyzed by a nuclear magnetic resonance (NMR) method. ) was 99.98 mol % or more.

(quantification of metal ions)
The EVOH-1 was pulverized by freeze pulverization. 10 g of the obtained EVOH-1 powder and 50 mL of deionized water were put into a 100 mL Erlenmeyer flask equipped with a common stopper, attached with a cooling condenser, and stirred and heated at 95° C. for 10 hours for extraction. 2 mL of the obtained extract was diluted with 8 mL of ion-exchanged water. The amount of each metal ion was quantified by manually analyzing the above-mentioned diluted extract at each observation wavelength shown below using an ICP emission spectrometer "Optima 4300 DV" manufactured by PerkinElmer Japan. .
Na: 589.592 nm
K: 766.490 nm
Mg: 285.213 nm
Ca: 317.933 nm
As a result, EVOH-1 contained sodium ions of 8.7 μmol/g (0.02 parts by mass with respect to 100 parts by mass of EVOH) as metal ions.

<Synthesis Example 2> Synthesis of Polyester B1 An aliphatic polyester (polyester B1), which is a copolymer of 1,4-butanediol and succinic acid, was obtained in accordance with the description of Production Example 8 of Japanese Patent No. 4,493,993. The obtained polyester B1 had a number average molecular weight of 69,700 and a melting point (Tm) of 108°C. Moreover, polyester B1 had a structural unit represented by the above formula (I) (n=4).

<Comparative Synthesis Example 1> Synthesis of polyester b1 In accordance with the description of Example 2 of JP-T-2011-518941, an aromatic polyester (a copolymer of 1,4-butanediol and dimethyl p-phthalate) ( A polyester b1) was obtained. The obtained polyester b1 had a number average molecular weight of 56,500 and a melting point (Tm) of 124°C. Moreover, the polyester b1 had a structural unit represented by the above formula (I) (n=4).

<Other polyester>
In addition, the following commercially available polyesters were used.
· Polyester B2: poly-ε-caprolactone manufactured by Wako Pure Chemical Industries, Ltd. (number-average molecular weight was 10,000, melting point (Tm) was 60 ° C. In addition, the above formula (I) (n = 5 ) It had a structural unit represented by.)
· Polyester B3: Disperplast 1018 manufactured by BYK-Chemie Japan Co., Ltd. (The number average molecular weight was 4,500, and the melting point (Tm) was 60 ° C. Also, represented by the above formula (I) (n = 4) It had a structural unit.)

<Example 1>
0.52 parts by mass of polyester B1 was added to 99.48 parts by mass of EVOH (mixture (EVOH-1) containing a metal salt obtained in Preparation Example), and dry blended to obtain the resin of Example 1. A pellet of the composition was obtained.

<Example 2>
0.52 parts by mass of polyester B1 is added to 99.48 parts by mass of EVOH (mixture (EVOH-1) containing metal salt obtained in Preparation Example), and a twin-screw extruder (Toyo Seiki Seisakusho Co., Ltd. "2D25W", D (mm) = 25, L/D = 20, extrusion temperature: 220°C), melt extrusion was performed under a nitrogen atmosphere to obtain pellets of the resin composition of Example 2.

<Examples 3 to 10, Comparative Examples 1 to 3>
Each resin of Examples 3 to 10 and Comparative Examples 1 to 3 was prepared in the same manner as in Example 1 except that the type of polyester used and the content (mixing ratio) of EVOH and polyester were as shown in Table 1. A pellet of the composition was obtained.

[evaluation]
(Thermoformability)
Each resin composition obtained in Examples 1 to 10 and Comparative Examples 1 to 3 was used as an intermediate layer, homopolypropylene [PP, "EA7AD" manufactured by Nippon Polypro Co., Ltd., MI = 1.4 g / 10 minutes (230 ° C., 2160 g Load)] are inner and outer layers, and maleic anhydride-modified polypropylene [Mitsui Chemicals “ADMER QF500”, MI = 5.3 g / 10 minutes (230 ° C., 2160 g load)] is an adhesive resin (AD) layer. A thermoforming sheet having a total thickness of 500 μm with 3 types and 5 layers (PP/AD/resin composition/AD/PP = thickness 230 μm/10 μm/20 μm/10 μm/230 μm) is produced by a co-extruder equipped with a T-shaped die. Obtained. The extruder and extrusion conditions are as follows.
Extruder:
Resin composition: Single-screw extruder (Toyo Seiki Co., Ltd. Lab machine ME type CO-EXT)
Caliber 20 mmφ, L/D = 20, screw full flight type PP: single screw extruder (Plastic Engineering Laboratory Co., Ltd. GT-32-A)
Diameter 32mmφ, L/D = 28, screw full-flight type AD: Single-screw extruder (Technobell Co., Ltd. SZW20GT-20MG-STD)
Diameter 20 mmφ, L/D = 20, screw full flight type Extrusion conditions:
Resin composition: feed section/compression section/measuring section/die = 175/210/220/230°C
PP: feeder/compressor/weigher/die=170/200/210/230°C
AD: feeder/compressor/weigher/die=150/200/220/220°C
The obtained sheet for thermoforming was thermoformed (compressed air: 5 kg) into a cup shape (mold shape: 70 φ × 70 mm, drawing ratio S = 1.0) at a sheet temperature of 170 ° C. with a thermoforming machine (manufactured by Asano Seisakusho). /cm ² , plug: 45φ×65 mm, syntax form, plug temperature: 150° C., mold temperature: 70° C.). The shape of the corners of the obtained compact was evaluated according to the following criteria. Table 1 shows the evaluation results.
A: It was stretched uniformly without becoming transparent.
B: Stretching was biased and partially transparent.

(Bleed-out suppression)
Using each resin composition obtained in Examples 1 to 10 and Comparative Examples 2 to 3 as a material, Toyo Seiki Seisakusho's extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 3.5, screw: full flight) was used to form a single layer film under the following conditions to obtain a single layer film.
Cylinder temperature: supply section 180°C, compression section 220°C, metering section 220°C
Die temperature: 220°C
Screw rotation speed: 40 rpm
Discharge rate: 1.2 kg/hour Take-up roll temperature: 80°C
Take-up roll speed: 3.0 m/min Film thickness: 20 µm

The resulting 20 μm monolayer film was stored for 7 days under conditions of 40° C./100% RH. After that, bleed-out was confirmed visually and by touch, and evaluated according to the following criteria. Table 1 shows the evaluation results.
A: Bleed-out did not occur.
B: Slight bleed-out was observed.
C: Remarkable bleeding out was observed.

As shown in Table 1 above, Examples 1 to 10 using a predetermined amount of aliphatic polyester (polyester B1, B2, or B3) had good thermoformability and the occurrence of bleed-out of the aliphatic polyester. is also found to be suppressed.

<Example 11>
EVOH (99.48 parts by weight) and Polyester B1 (0.52 parts by weight) were dry blended. Then, 100 parts by mass of this mixture (dispersion medium) was mixed with phosphoric acid as metal compound particles using a twin-screw extruder (Super TEX 44αII, L/D = 45.5, die temperature: 220 ° C., manufactured by JSW Japan Steel Works, Ltd.). Melt extrusion was performed in a nitrogen atmosphere while side-feeding 4.71 parts by mass of disodium hydrogen particles (average particle size: 2.8 μm). Thus, pellets of the resin composition of Example 11 were obtained. EVOH was subjected to dry blending as a mixture (EVOH-1) containing a metal salt obtained in Preparation Examples.

Regarding the pellets of the obtained resin composition, each metal ion was quantified by the same method as in the above "quantification of metal ions". The total amount of each metal ion can be regarded as the content of the metal element of the metal compound in the obtained resin composition. The content of the metal element (C') in the metal compound (C) in the obtained resin composition was 1.48 parts by mass with respect to the total of 100 parts by mass of EVOH and polyester B1. The metal element includes the metal element in the metal salt and the metal element in the metal compound particles.

<Example 12>
Dry blend of EVOH (99.48 parts by mass), polyester B1 (0.52 parts by mass), and 4.71 parts by mass of disodium hydrogen phosphate particles (average particle size 2.8 μm) as metal compound particles did. Then, this mixture was melt-extruded under a nitrogen atmosphere using a twin-screw extruder (Super TEX 44αII, L/D=45.5, die temperature: 220° C. manufactured by JSW Japan Steel Works, Ltd.). Thus, pellets of the resin composition of Example 12 were obtained. EVOH was subjected to dry blending as a mixture (EVOH-1) containing a metal salt obtained in Preparation Examples.

Regarding the pellets of the obtained resin composition, each metal ion was quantified by the same method as in the above "quantification of metal ions". The content of the metal element (C') in the metal compound (C) in the obtained resin composition was 1.48 parts by mass with respect to the total of 100 parts by mass of EVOH and polyester B1.

<Example 13>
EVOH (99.48 parts by weight) and Polyester B1 (0.52 parts by weight) were dry blended. Then, 100 parts by mass of this mixture (dispersion medium) was mixed with phosphoric acid as metal compound particles using a twin-screw extruder (Super TEX 44αII, L/D = 45.5, die temperature: 220 ° C., manufactured by JSW Japan Steel Works, Ltd.). Melt extrusion was performed in a nitrogen atmosphere while adding an aqueous solution of 4.71 parts by mass of disodium hydrogen particles (average particle size: 2.8 μm). Thus, pellets of the resin composition of Example 13 were obtained. EVOH was subjected to dry blending as a mixture (EVOH-1) containing a metal salt obtained in Preparation Examples.

Regarding the pellets of the obtained resin composition, each metal ion was quantified by the same method as in the above "quantification of metal ions". The content of the metal element (C') in the metal compound (C) in the obtained resin composition was 1.48 parts by mass with respect to the total of 100 parts by mass of EVOH and polyester B1.

<Examples 14 to 25, Comparative Examples 4 to 7>
Example 14 was prepared in the same manner as in Example 11 except that the types of polyester and metal compound particles used and the contents (mixing ratio) of metal elements in EVOH, polyester and metal compound were as shown in Table 2. Pellets of each resin composition of 1 to 25 and Comparative Examples 4 to 7 were obtained. Table 2 shows the molar ratio (Ma/Mc) between the vinyl alcohol unit (Ma) in the EVOH and the metal element (Mc) in the metal compound (C) in each resin composition, and the aliphatic polyester (B) and The mass ratio (B/C') to the metal element (C') in the metal compound (C) is also shown. The content of the metal compound was adjusted by adjusting the amount of the metal compound particles to be blended. A commercially available product was used for each metal compound particle. The particle size of the metal compound particles was appropriately adjusted by pulverization.

[evaluation]
(Adhesion amount to the screw)
Using the resin compositions obtained in Examples 11 to 25 and Comparative Examples 4 to 7 as materials, Toyo Seiki Seisakusho's extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight), a single layer film was formed under the following conditions to obtain a single layer film.
Cylinder temperature: supply section 180°C, compression section 220°C, metering section 220°C
Die temperature: 220°C
Screw rotation speed: 40 rpm
Discharge rate: 1.2 kg/hour Take-up roll temperature: 80°C
Take-up roll speed: 3.0 m/min Film thickness: 20 µm

After extruding the monolayer film for 48 hours, 2 kg of LDPE (“Novatec LD LA320” manufactured by Nippon Polyethylene Co., Ltd.) was continuously added, and the extruder, adapter and die were purged. After the LDPE had run out, the operation was stopped, the screw was taken out, the LDPE remaining on the screw was removed, the deteriorated screw deposits were collected, and the mass of the obtained screw deposits was weighed. Table 2 shows the adhesion amount. The amount of adhesion to the screw is an index of the amount of deterioration products generated, and the smaller the amount of adhesion to the screw, the better the appearance of the molded product obtained, and the less likely problems such as fish eyes and streaks will occur.

(full width at half maximum of pellet)
As an index for suppressing variation in pellet size, the particle size distribution of the equivalent circle diameter (radius) of the pellets of each resin composition obtained in Examples 11 to 25 and Comparative Examples 4 to 7 was measured according to Verder Scientific's " CAMSIZER XT", it was obtained from the circle equivalent diameter calculated by the dynamic image analysis method based on ISO 13322-2 (2006). The above measurements were carried out using 500 g of resin composition pellets. The full width at half maximum (mm) was obtained from the obtained particle size distribution. Table 2 shows the measured values.

(Oxygen permeation rate after retort treatment)
As an evaluation of the oxygen barrier property, the oxygen permeation rate after retort treatment was measured. First, each resin composition obtained in Examples 11 to 25 and Comparative Examples 4 to 7 was used as an intermediate layer, homopolypropylene [PP, "EA7AD" manufactured by Nippon Polypro Co., Ltd., MI = 1.4 g / 10 minutes (230 ° C. , 2160 g load)] are used as inner and outer layers, and maleic anhydride-modified polypropylene [Mitsui Chemicals "Admer QF500", MI = 5.3 g / 10 minutes (230 ° C., 2160 g load)] is an adhesive resin (AD) layer. Then, a multi-layer sheet with a total thickness of 500 μm with 3 types and 5 layers (PP / AD / resin composition / AD / PP = thickness 368 μm / 16 μm / 32 μm / 16 μm / 368 μm) is produced by a co-extruder equipped with a T-shaped die. Obtained. The extruder and extrusion conditions are as follows.
Extruder:
Resin composition: Single-screw extruder (Toyo Seiki Co., Ltd. Lab machine ME type CO-EXT)
Caliber 20 mmφ, L/D = 20, screw full flight type PP: single screw extruder (Plastic Engineering Laboratory Co., Ltd. GT-32-A)
Diameter 32mmφ, L/D = 28, screw full-flight type AD: Single-screw extruder (Technobell Co., Ltd. SZW20GT-20MG-STD)
Diameter 20 mmφ, L/D = 20, screw full flight type Extrusion conditions:
Resin composition: feed section/compression section/measuring section/die = 175/210/220/230°C
PP: feeder/compressor/weigher/die=170/200/210/230°C
AD: feeder/compressor/weigher/die=150/200/220/220°C

The resulting multilayer sheet was cut into 10 cm×10 cm pieces and placed on a shelf of a retort sterilizer (“RCS-60-10RSTXG-FAM” manufactured by Hisaka Seisakusho Co., Ltd.). Then, a hot water retort sterilization treatment in which the cut multilayer sheet was completely immersed in hot water was performed under the following conditions.
Retort treatment temperature: 120°C
Time: 30 minutes Pressure: 0.15 MPa
The multilayer sheet after the retort treatment was conditioned for 2 months under the conditions of 20° C., 100% RH inner layer/65% RH outer layer. Thereafter, the oxygen permeation rate was measured under the same conditions using Mocon's "OX-TORAN MODEL 2/21" according to the method described in JIS K 7126 (isobaric method). The measurement result was converted into an oxygen permeation rate per 20 μm layer of the resin composition. Table 2 shows the measurement results.

As shown in Table 2 above, in Examples 11 to 25, the amount of adhesion to the screw was small, and the full width at half maximum of the pellets was a small value. It can be seen that the resin compositions of Examples 11 to 25 can be stably melt-molded and are excellent in melt-moldability. In addition, it can be seen that Examples 11 to 25 also have high oxygen shielding properties after retort treatment.

In addition, when compared among Examples 11 and 14 to 25 produced by the same production method (method of adding metal compound particles), the content of the metal element (C') in the metal compound (C) is relatively small or large. , Examples 17, 23 and 24 in which the particle size of the metal compound particles is relatively large and the molar ratio (Ma/Mc) is relatively small or large, and the mass of the aliphatic polyester (B) and the content of the metal compound (C) Examples 15 and 19 to 22, in which the ratio (B/C') to the mass of the metal element (C') is relatively small or large, resulted in slightly inferior results.

In addition, when comparing Examples 11 to 13 with different production methods (methods of adding metal compound particles), Example 10 in which metal compound particles are mixed by melt-kneading a dispersion medium containing EVOH, a metal salt, and an aliphatic polyester. It was found that the resin composition obtained by is most effective.

The resin composition of the present invention can be suitably used as a molding material for films, sheets, containers and the like.

Claims (8)

Ethylene-vinyl alcohol copolymer (A);
an aliphatic polyester (B) having a number average molecular weight (Mn) of 1,000 or more and 100,000 or less and a melting point of 40° C. or more and 120° C. or less, and having a structural unit represented by the following formula (I) ;
with a metal compound (C)
contains
The content of the aliphatic polyester (B) with respect to a total of 100 parts by mass of the ethylene-vinyl alcohol copolymer (A) and the aliphatic polyester (B) is 0.01 parts by mass or more and less than 30 parts by mass. ,
The content of the metal element (C') in the metal compound (C) with respect to a total of 100 parts by mass of the ethylene-vinyl alcohol copolymer (A) and the aliphatic polyester (B) is 0.05 parts by mass or more. 20 parts by mass or less,
The metal compound (C) contains metal compound particles (C2),
The metal compound particles (C2) are sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium sulfate, sodium pyrophosphate, disodium succinate, sodium tartrate, trisodium citrate, magnesium sulfate, trimagnesium dicitrate, silicon magnesium phosphate, trimagnesium phosphate, magnesium succinate, calcium lactate, nanoclay, sodium phosphate, sodium polyphosphate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, lithium polyphosphate, potassium phosphate, phosphorus dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium polyphosphate, calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium polyphosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium polyphosphate Or a resin composition that is a combination thereof.
—(CH ₂ ) _n —OCO— (I)
(In formula (I), n represents an integer of 2 to 6.) The molar ratio (Ma/Mc) between the vinyl alcohol unit (Ma) in the ethylene-vinyl alcohol copolymer (A) and the metal element (Mc) in the metal compound (C) is 0.01 or more and 500 or less. The resin composition according to claim 1 . The resin composition according to claim 1 , wherein the mass ratio (B/C') between the aliphatic polyester (B) and the metal element (C') in the metal compound (C) is 0.0005 or more and 5 or less. thing. The resin composition according to Claim 1 , wherein the metal component of the metal compound (C) comprises sodium, magnesium, aluminum, potassium, calcium, or a combination thereof. The metal compound particles (C2) are sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium sulfate, sodium pyrophosphate, disodium succinate, sodium tartrate, trisodium citrate, magnesium sulfate, trimagnesium dicitrate, silicon 2. The resin composition of claim 1 , which is magnesium phosphate, trimagnesium phosphate, magnesium succinate, calcium lactate, nanoclay, or a combination thereof. A laminate comprising: a barrier layer made of the resin composition according to claim 1; and a layer containing a thermoplastic resin disposed on at least one side of the barrier layer. A package comprising the laminate according to claim 6 . The package according to claim 7 , which is for retort.